Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

C57BL/6 and AKR mice were treated with hamster erythrocytes (HRBC) in complete Freund's adjuvant (CFA) or incomplete Freund's adjuvant (IFA) and the development of delayed hypersensitivity and antibody production were examined. 1) Delayed hypersensitivity against HRBC antigen, as determined by the peritoneal macrophage disappearance test, was detected in mice sensitized with HRBC in CFA but not in those sensitized with HRBC in IFA. 2) Antibody production against HRBC or hapten TNP after a booster injection of HRBC or trinitrophenylated HRBC (TNP-HRBC) in saline was enhanced by pretreatment with HRBC in CFA or IFA. 3) Delayed hypersensitivity was not detectable after a booster sensitization with HRBC in CFA in mice which had been pretreated with HRBC in IFA 2 weeks earlier. In the mice treated with both HRBC in IFA (day ?21) and in CFA (day ?7), however, an enhanced antibody production against HRBC or TNP was detected after an intravenous injection with HRBC or TNP-HRBC in saline (day 0). These results suggest that sensitized effector lymphocytes in delayed hypersensitivity and helper cells in antibody production may be derived from the same pool of unprimed T cells. The pool of unprimed T cells with a capacity to differentiate into either type of primed T cells may be exhausted after pretreatment with the antigen in IFA, and the primed helper T cells may not be able to differentiate into sensitized lymphocytes even after sensitization with the antigen in CFA, which favors development of delayed hypersensitivity in normal controls.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

Antibody response against hamster red blood cells (H-RBC) was examined in inbred strains of C57BL/6, AKR, C3H/He, DDD and SL mice, and outbred CF1 mice. 1) There were strain differences in antibody response after a primary intravenous injection of H-RBC. DDD, SL and CF1 mice belonged to high-responder strains, while C57BL/6, AKR and C3H/He to low-responder strains. In the spleens of immunized CF1 and SL, 40 to 70 times as many plaque-forming cells (PFC) as those in C57BL/6 mice were detected. The magnitudes of the response were: CF1 ≒ SL>DDD>>C3H/He ? AKR>C57BL/6. 2) 2-mercaptoethanol resistant (MER) antibody was detected in neither low- nor high-responders after a primary intravenous antigen-injection. 3) After a secondary intravenous antigen-injection, MER antibody was detected in all the SL mice, but only in 30 to 50% of AKR and C57BL/6 mice. 4) A subcutaneous injection of H-RBC in Freund's complete adjuvant (FCA) did not elicit antibody production within 10 days. When mice pre-sensitized 7 days in advance w^Tith H-RBC in FCA were intravenously injected with H-RBC, enhanced antibody production of the primary type was observed in all the mouse strains. 5) In pre-sensitized mice, the extent of the enhancement of antibody production was the highest in low-responder C57BL/6 mice and the lowest in high-responder SL and CF1 strains. Thus, there was no strain difference in antibody titers or the numbers of PFC after the booster.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

In a previous paper we reported that an inbred strain of SL mice and an outbred strain of CF1 mice belonged to the high-responder strains in antibody production after primary immunization with hamster erythrocytes (H-RBC), while inbred strains of C57BL/6, AKR and C3H/He mice belonged to low-responder strains. In the present study we obtained the following results. 1) Pre-sensitization with hamster lymphoma enhanced antibody production after an intravenous injection of H-RBC. There was no strain difference in the pattern of antibody production against H-RBC among pre-sensitized mice. 2) The pattern of enhanced antibody production after an intravenous injection of H-RBC into pre-sensitized mice assumed the primary type in terms of time of appearance of hemolysin plaque-forming cells (PFC) in the spleens and the conversion from 2-mercaptoethanol sensitive to 2-mercaptoethanol resistant antibody production, when the intervals between both treatments were within 7 days. 3) Pre-sensitization with lymphoma induced not only an increase in numbers of PFC after an intravenous injection of H-RBC, but also an increase in the size of the hemolysin plaques. These results suggested that sensitization with hamster lymphoma stimulated some kinds of immuno-competent cells, which could contribute to antibody production against H-RBC after a booster injection of H-RBC.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

Patterns of proliferation of antibody-forming cells after an intravenous immunization with hamster erythrocytes (HRBC) were compared in groups of mice possessing different activities of thymus-derived lymphocytes (T cells). 1) Marked differences in the numbers of hemolysin plaque-forming cells (PFC) after HRBC injection were found among the low- and high-responder normal mice and those pretreated with HRBC in complete Freund's adjuvant (CFA) or incomplete adjuvant (IFA), and they appeared to depend primarily upon the different rates of proliferation of antibody-forming cells rather than on the numbers of antigen-specific lymphocytes initiating the antibody response. 2) The numbers of hemolytic foci were slightly larger in mice with large numbers of PFC (normal SL mice, the pretreated SL and C57BL/6 mice) than in those with small numbers of PFC (normal C57BL/6 mice). The numbers of hemolytic foci increased at almost the same rate from day 2 to day 3 in both groups, while the numbers of PFC increased more efficiently in mice with large numbers of PFC than in those with small numbers of PFC from day 2 to day 3. Individual hemolytic foci appeared to contain larger numbers of PFC in mice with large total numbers of PFC than in those with small total numbers of PFC. 3) The numbers of rosette-forming cells (RFC) were increased by pretreatment with HRBC in CFA and by pretreatment with HRBC in IFA to almost the same extent. Rates of increases in PFC were, however, larger by pretreatment with HRBC in CFA than with HRBC in IFA. These results suggested that the activity of the T cell determined not only the rates of proliferation of antibody-forming cells but also the antibody-producing capacity of each cell.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

Golden hamsters were used as hosts in this work, and mice of various strains as donors of antigens. 1) There were no strain differences in immunogenicity of erythrocytes from C57BL/6, AKR, SL and CF1 mice. 2) Primary intravenous immunization with mouse erythrocytes (MRBC) induced the production of hemolysin plaque-forming cells (PFC) in a large number, but elicited only in a negligible titer production of 2-mercaptoethanol-resistant antibody. 3) 2-Mercaptoethanol-resistant antibody was produced more efficiently in hamsters pre-sensitized with mouse lymph node (MLN) cells rather than those pre-immunized with MRBC after a booster with MRBC. 4) Numbers of PFC in pre-sensitized hamsters were three-times that of the non-sensitized hamsters after a booster with MRBC, when pre-sensitization was performed intradermally with a small number of MLN cells. 5) Average diameter of the hemolysin plaques in pre-sensitized hamsters was one and a half times larger than that in non-sensitized hamsters. Conclusions agree well with the results in our previous papers that the reversed combination of hosts and antigen donors employed support the concept that certain processes required for delayed hypersensitivity contributed to antibody production under a condition suitable for antibody response.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

The production of anti-hapten antibody after immunization with trinitrophenylated (TNP) hamster erythrocytes (HRBC) or sheep erythrocytes (SRBC) was determined in high- and low-responder mouse strains against HRBC antigen. 1) Anti-TNP antibody was detected in sera of high-responder DDD and CF1 mice after primary immunization with TNP-HRBC, but not in those of low-responder C57BL/6 mice. 2) Anti-TNP antibody was detectable in sera of all the strains after primary immunization with TNP-SRBC. 3) Production of anti-TNP antibody was elicited after a booster injection of TNP-HRBC in low-responder C57BL/6 mice pre-sensitized with HRBC in Freund's complete adjuvant. These results suggest that functions of thymus-derived cells specific for HRBC antigen are deficient in low-responder mice.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

Enhancing and suppressing effects of microbial adjuvants were studied in female mice of the C3H/He, AKR and SL strains. Propionibacterium acnes, Bordetella pertussis, BCG and yeast cell wall (YCW) were chosen as adjuvants. As antigens, we chose hamster erythrocytes (HRBC) which proved to be a weak antigen for mice. Adjuvants were given on day —7, day 0 or day 3, and HRBC were injected on day 0. The results were as follows. 1) P. acnes facilitated IgM and IgG antibody production in AKR mice and suppressed IgM antibody production in SL mice, when given on day —7. When P. acnes was given on day 0, they suppressed IgM antibody production in all of the strains used. 2) When B. pertussis was given on day 0, it exhibited enhancing effects on IgG antibody production in all of the strains and a suppressing effect on IgM antibody production in SL mice. 3) BCG suppressed IgM antibody production in all strains when given on day 0. 4) YCW showed no influence on antibody production in any combination used in this work. 5) SL mice were very sensitive to suppressing effects by adjuvants. Strain differences in the expression of enhancing and suppressing effects by adjuvants appear to be under some control independent of antigen-specific immune response genes.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

Delayed hypersensitivity against hamster erythrocyte antigen was examined after sensitization with hamster erythrocytes (HRBC) in Freund's complete adjuvant (FCA). Extent of the delayed hypersensitivity was determined by the migration inhibition test, the peritoneal macrophage disappearance test and the skin test in the ear using solubilized HRBC as the test antigen. 1) Delayed hypersensitivity against HRBC developed earlier in high-responder SL mice than in low-responder C57BL/6 mice after sensitization. The period required for development of the delayed hypersensitivity in AKR mice was intermediate between periods in high-responder SL mice and low-responder C57BL/6 mice. 2) After sensitization with HRBC in FCA, a delayed hypersensitive state without detectable antibody production persisted until day 12 in high-responder SL mice and until day 16 or later in low-responder C57BL/6 mice. 3) Delayed hypersensitivity against HRBC antigen persisted even after the appearance of circulating antibody which occurred late after sensitization with HRBC in FCA or after intravenous injection of HRBC into sensitized mice.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

It was confirmed by passive transfer experiments that the function of thymus-derived cells specific for hamster erythrocytes (HRBC) was deficient in the low-responder mouse strains. 1) Antibody production against HRBC was enhanced by passive transfer of thymus cells from normal SL mice (high-responder) to normal C57BL/6 mice (low-responder). 2) The enhancing effect of passive transfer of thymus cells from SL mice was abrogated by pre-sensitization of the recipients (C57BL/6) with thymus cells from SL mice. 3) In C57BL/6 mice, antibody production against HRBC was enhanced by the transfer of lymph node or spleen cells from C57BL/6 mice which had been sensitized with HRBC in Freund's complete adjuvant or hamster lymphoma cells.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

1) A subcutaneous injection of hamster erythrocytes (HRBC) in Freund's complete adjuvant (FCA) or an intravenous injection of hamster lymph node (HLN) cells suppressed antibody production against HRBC in the low-responder C57BL/6 and AKR mice, when HRBC in saline were given on the same day; 2) The suppressing effect of such treatments was neither detectable in the high-responder SL mice, nor in the C57BL/6 mice, which had been pre-sensitized with HRBC in FCA or hamster lymphoma cells; 3) Positive reactions of the peritoneal macrophage disappearance test and the enhanced antibody production were detected seven days after treatment with HRBC in FCA and HRBC in saline, or HLN cells and HRBC in saline; 4) The suppressing effect of such simultaneous treatments on anti-HRBC antibody production was eliminated by a transfer of normal syngeneic thymus cells to AKR mice or a transfer of thymus cells from SL to C57BL/6 mice. Suppression of the antibody production in the low-responder mice by the described simultaneous treatments may be due to a competitive involvement of HRBC-specific thymus-derived cells (T cells) in the developmental stages of delayed hypersensitivity and antibody production. High-responder SL mice appear to have enough T cells for development of the delayed hypersensitivity and as helper cells in antibody production. These results appear to support the concept that T cells for delayed hypersensitivity and antibody production to HRBC antigen are derived from the same original pool.     

Characteristic Immune Response in Peyer’s Patch Cells Induced by Oral Administration of Bifidobacterium Components

We demonstrate immunomodulatory effects, especially those involving murine intestinal IgA secretion, in Peyer's patch cells following oral administration of Bifidobacterium immunomodulator (BIM) derived from sonicated B. pseudocatenulatum 7041. BALB/c mice were administered BIM orally for 7 consecutive days. The PP cells demonstrated upregulated secretion of total IgA including BIM-specific IgA following BIM administration. In observing the response of PP cells co-cultured with BIM, we found enhanced secretion of interferon-γ (IFN-γ) and interleukin (IL)-6 in the CD4⁺ T cells. In contrast, IL-12 secretion by Thy1.2⁻ PP cells was enhanced, but secretion of IFN-γ, IL-5, and IL-6 was not significantly affected. Furthermore, the population of CD4⁺ CD45RB^high T cells in PP increased following oral administration of BIM. These data suggest that CD4⁺ T cells were affected by BIM administration. Overall, the results show that oral administration of BIM induced CD4⁺ PP cells to change their expression of cell surface antigen and cytokine production.     

Screening of Exopolysaccharide-Producing Lactobacillus and Bifidobacterium Strains Isolated from the Human Intestinal Microbiota

Using phenotypic approaches, we have detected that 17% of human intestinal Lactobacillus and Bifidobacterium strains could be exopolysaccharide (EPS) producers. However, PCR techniques showed that only 7% harbored genes related to the synthesis of heteropolysaccharides. This is the first work to screen the human intestinal ecosystem for the detection of EPS-producing strains.     

Bifidobacterium ruminantium sp. nov. and Bifidobacterium merycicum sp. nov. from the rumens of cattle

Among several hundred bifidobacteria isolated from bovine rumens, eight strains were recognized primarily on the basis of DNA-DNA hybridization results as members of two new distinct DNA homology groups. We studied the morphology, oxygen, carbon dioxide, temperature, and pH requirements, fermentation patterns, end products of glucose fermentation, biochemical reactions, protein electrophoretic patterns, isozyme patterns, DNA homology relationships, and guanine-plus-cytosine contents of these organisms, and we propose that these two groups of strains should be considered new species, Bifidobacterium ruminantium (type strain, strain ATCC 49390) and Bifidobacterium merycicum (type strain, strain ATCC 49391).     

Immune Response Suppression by an Inhibitor in Normal and Immune Mouse Serum

CONTROL mechanisms responsible for determining the intensity and duration of the immune response have been studied extensively. Jerne¹ and Uhr and Möller² described the phenomenon of feedback inhibition whereby the production of a 7S class of antibodies terminates the formation of antibodies with the same specificity. An immunosuppressive effect has also been observed in antigenic competition, in which the administration of one antigen results in a reduced response to a subsequently administered second antigen³. Recently, several investigations have focused on the mechanism of antigenic competition^4,5. A humoral rather than cellular mechanism is generally believed to be responsible for this phenomenon^4–6, but attempts to identify the humoral mediator have been unsuccessful. We have also searched for a humoral substance responsible for the immunosuppressive effect in antigenic competition and found in the sera of adult untreated mice an immunosuppressive agent whose concentration was substantially increased after antigenic stimulation.     

Attachment and Biofilm Forming Capabilities of Staphylococcus epidermidis Strains Isolated from Preterm Infants

Staphylococcus epidermidis, a human commensal, is an important opportunistic, biofilm-forming pathogen and the main cause of late onset sepsis in preterm infants, worldwide. In this study we describe the characteristics of S. epidermidis strains causing late onset (>72 h) bloodstream infection in preterm infants and skin isolates from healthy newborns. Attachment and biofilm formation capability were analyzed in microtiter plates and with transmission electron microscopy (TEM). Clonal relationship among strains was studied with pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was performed, as well as the detection of biofilm-associated genes and of the invasiveness marker IS256 with polymerase chain reaction. Blood and skin isolates had similar attachment and biofilm-forming capabilities and biofilm formation was not related to the presence of specific genes. Filament-like membrane structures were seen by TEM early in the attachment close to the device surface, both in blood and skin strains. Nine of the ten blood isolates contained the IS256 and were also resistant to methicillin and gentamicin in contrast to skin strains. S. epidermidis strains causing bloodstream infection in preterm infants exhibit higher antibiotic resistance and are provided with an invasive genetic equipment compared to skin commensal strains. Adhesion capability to a device surface seems to involve bacterial membrane filaments.     

人巨细胞病毒DNA疫苗免疫效果的初步研究

人巨细胞病毒(HCMV)是广泛感染人类的重要病原体之一,在人群中有较高的感染率,胎儿、婴儿、器官移植及免疫缺陷者等更易感染.现有的抗HCMV药物治疗及被动免疫由于毒性大、价格昂贵及短效性等原因,应用大受限制,为此研制安全、有效的疫苗即成为防治HCMV疾病的重要手段.HCMV具有潜在的致癌作用,不宜发展活疫苗或含完整病毒DNA的死疫苗;亚单位疫苗虽然比较安全,但所用抗原不能在宿主细胞内表达,只能诱导体液免疫,这对于胞内感染的HCMV预防效果较差;通过新佐剂的应用,虽可引发细胞免疫,但免疫原性较差,且成本较高.因此,目前倾向于研制具有免疫原性的HCMV DNA疫苗.     

Characterization of Bifidobacterium apousia sp. nov., Bifidobacterium choladohabitans sp. nov., and Bifidobacterium polysaccharolyticum sp. nov., three novel species of the genus Bifidobacterium from honey bee gut

Bifidobacterium is one of the dominating bacterial genera in the honey bee gut, and they are the key degrader of diet polysaccharides for the host. Previous genomic analysis shows that they belong to separate phylogenetic clusters and exhibited different functional potentials in hemicellulose digestion. Here, three novel strains from the genus Bifidobacterium were isolated from the guts of the honey bee (Apis mellifera). Phylogenomic analysis showed that the isolates could be grouped into four phylogenetic clusters. The average nucleotide identity values between strains from different clusters are <95%, while strains in Cluster IV belong to the characterized species Bifidobacterium asteroides. Carbohydrate-active enzyme annotation confirmed that the metabolic capacity for carbohydrates varied between clusters of strains. Cells are Gram-positive rods; they grew both anaerobically and in a CO₂-enriched atmosphere. All strains grew at a temperature range of 20–42 °C, with optimum growth at 35 °C. The pH range for growth was 5–9. Strains from different phylogenetic clusters varied in multiple phenotypic and chemotaxonomic characterizations. Thus, we propose three novel species Bifidobacterium apousia sp. nov. whose type strain is W8102^T (=CGMCC 1.18893 ^T = JCM 34587 ^T), Bifidobacterium choladohabitans sp. nov., whose type strain is B14384H11^T (=CGMCC 1.18892 ^T = JCM 34586 ^T), and Bifidobacterium polysaccharolyticum sp. nov. whose type strain is W8117^T (=CGMCC 1.18894 ^T = JCM 34588 ^T).     

Bifidobacterium reuteri sp. nov., Bifidobacterium callitrichos sp. nov., Bifidobacterium saguini sp. nov., Bifidobacterium stellenboschense sp. nov. and Bifidobacterium biavatii sp. nov. isolated from faeces of common marmoset (Callithrix jacchus) and red-handed tamarin (Saguinus midas)

Five strains of bifidobacteria were isolated from faeces of a common marmoset (Callithrix jacchus) and a red-handed tamarin (Saguinus midas). The five isolates clustered inside the phylogenetic group of the genus Bifidobacterium but did not show high sequence similarities between the isolates and to known species in the genus by phylogenetic analysis based on 16S rRNA gene sequences. Sequence analyses of dnaJ1 and hsp60 also indicated their independent phylogenetic positions to each other in the Bifidobacterium cluster. DNA G+C contents of the species ranged from 57.3 to 66.3 mol%, which is within the values recorded for Bifidobacterium species. All isolates showed fructose-6-phosphate phosphoketolase activity. Based on the data provided, the five isolates represent five novel species, for which the names Bifidobacterium reuteri sp. nov. (type strain: AFB22-1(T) = JCM 17295(T) = DSM 23975(T)), Bifidobacterium callitrichos sp. nov. (type strain: AFB22-5(T) = JCM 17296(T) = DSM 23973(T)), Bifidobacterium saguini sp. nov. (type strain: AFB23-1(T) = JCM 17297(T) = DSM 23967(T)), Bifidobacterium stellenboschense sp. nov. (type strain: AFB23-3(T) = JCM 17298(T) = DSM 23968(T)) and Bifidobacterium biavatii sp. nov. (type strain: AFB23-4(T) = JCM 17299(T) = DSM 23969(T)) are proposed.